As an example of article transport devices described above, JP Publication of Application No. 2011-157184 (Patent Document 1) describes conveyors for carrying articles into and out of a stocker for storing articles.
As shown in FIG. 5 of Patent Document 1, the conveyors of Patent Document 1 have a housing in which frame members are located at four corners as seen along the transport direction with each frame member formed to be long such that its longitudinal direction is along the transport direction. While not described in detail in Patent Document 1, a known example of a conventional conveyor having such a housing is shown in FIGS. 10 and 11 of the present application. More specifically, the conveyor has a housing in which frame members 200Y are located at four corners of the housing as seen along the transport direction with each frame member 200Y formed to be long such that its longitudinal direction is along the transport direction and with a bottom plate 201, side plates 202, and a top surface plate 203 attached to the frame member 200Y. As shown in FIGS. 10 and 11, a travel carriage D which travels through an accommodating space inside the housing and along the transport direction is provided in the conveyor. And a support member 54 for supporting an article from below is provided at the upper end of the travel carriage D such that the support member 54 can be moved vertically. Further, an opening 200G is provided in the top surface of the housing through which the support member 54 can project upward beyond the opening 200G. When performing maintenance work on a transport mechanism in such a conveyor, the transport mechanism is often accessed through the opening formed in the top surface of the housing.